Sensorineural Hearing Loss

1. See Also
   1. Hearing Loss
   2. Conductive Hearing Loss
2. Epidemiology
   1. Age of onset over 40 years old
3. Causes
   1. Presbycusis related to aging (bilateral)
   2. Noise induced Hearing Loss (bilateral)
   3. Cranial Nerve 8 disease
      1. Meniere's Disease
      2. Acoustic Neuroma
   4. Viral
      1. Mumps
   5. Hematologic from vascular sludging and Hypoxia
      1. Polycythemia Vera
      2. Sickle Cell Anemia
      3. Leukemia
      4. Hypercoagulable states
   6. Microvascular disease
      1. Diabetes Mellitus
      2. Hyperlipidemia
   7. Ototoxic Medications (bilateral)
   8. Infectious Causes
      1. Tertiary Syphilis
      2. Lyme Disease
   9. Endocrine Disease
      1. Hypothyroidism
   10. Autoimmune Hearing Loss
   11. Congenital deafness
   12. Trauma
       1. Temporal BoneFracture involving Cochlea or vestibule
       2. Perilymph fistula
          1. Round window or oval window rupture with leak
          2. Caused by trauma, lifting, straining, coughing
4. Symptoms
   1. Tinnitus
      1. Ringing, buzzing, humming, hissing, "crickets in ears"
      2. Occurs early in Hearing Loss course
   2. Pain with loud noise exposure
   3. Frequently ask others to repeat what they have said
   4. Impaired word understanding often present
   5. Loud patient's voice
   6. Hearing difficult in noisy environments
5. Signs
   1. Otoscopy
      1. Ear Canal and TM are normal
   2. Weber Test (Tuning Fork at Midline) Abnormal
      1. Sound radiates to ear with less sensorineural loss
   3. Rinne Test (Tuning Fork on Mastoid) Abnormal
      1. Both air conduction and bone conduction reduced
6. Labs
   1. Complete Blood Count (CBC)
   2. Erythrocyte Sedimentation Rate (ESR)
   3. Thyroid Stimulating Hormone (TSH)
   4. Urinalysis
   5. Serum Glucose
   6. Renal Function,
   7. Cholesterol and Triglycerides
   8. Syphilis Serology (VDRL or RPR)
   9. Lyme Titer (if suggested by history)
7. Imaging
   1. MRI Head at Internal Auditory Canal (IAC)
      1. Gold standard to evaluate for Acoustic Neuroma
      2. Evaluates for inflammation such as due to Herpes Zoster Oticus
      3. Vascular lesions may be evident
   2. MRA head
      1. Indicated if vascular lesion is suspected
   3. CT Temporal Bone
      1. Evaluates infectious causes (e.g. Mastoiditis, Cholesteatoma)
      2. Evaluates bone anatomy (ossicles and Cochlea, vestibular aqueduct swelling, Fractures)
      3. Can also identify Acoustic Neuroma and vascular lesions but MRI is preferred
8. Management
   1. Formal audiology testing
   2. Acute Hearing Loss (within 3 days)
      1. Urgent evaluation needed for 30 db loss
      2. High dose Steroids (1 mg/kg/d) (uncertain efficacy)
      3. Carbogen Inhalation (5% CO2 and 95% Oxygen)
         1. May increase Cochlear blood flow by vasodilation
         2. Duration determined by serial Audiograms
      4. Otolaryngology evaluation
   3. Chronic
      1. See Hearing Aid
9. Course
   1. Often no etiology identified
   2. May resolve spontaneously
10. Resources
    1. Hearing Loss Sampler
       1. http://facstaff.uww.edu/bradleys/radio/hlsimulation/